Experiments will be carried out to determine the effects of the hepatotoxic agent dimethylnitrosamine and the carcinogenic agent dimethylaminoazobenzene on the ability of liver cells to form glycogen from glucose, lactate or alanine. In addition, their effects on the enzymes of glycagen metabolism, including glycogen synthetase phosphatase and phosphorylase phosphatase will be measured. These experiments will be done both with intact rats and with isolated rat liver cells obtained by enzyme disruption of hepatic connective tissue. Initial experiments have indicated that the amount of gluconeogenesis from alanine is not affected by the apparent loss of liver cells caused by the hepatotoxic agents carbon tetrachloride and thioacetamide or by the real loss of liver cells resulting from partial hepatectomy. These findings suggest an increased rate of gluconeogenesis in livers of treated rats. An explanation for this increase will be sought by measuring the metabolites involved in gluconeogenesis both in livers of intact rats, in cells isolated from treated rats and in isolated cells to which the hepatotoxic agent is added in vitro.